Law of Diminishing Marginal Utility

The Law of Diminishing Marginal Utility suggests that when an individual continues to consume additional units of a product or service, the satisfaction gained from each successive unit tends to fall. The initial unit typically delivers the greatest sense of benefit, but as consumption continues, the utility added by each new unit steadily diminishes. Over time, the extra satisfaction may become negligible or even negative, indicating that the individual no longer desires more of that good.

Illustration:

Consider someone eating slices of pizza. The first slice satisfies their hunger the most. The next slice still tastes good but is slightly less rewarding. As they continue eating, each additional slice contributes less enjoyment than the previous one, and eventually they may reach a point where they do not want any more pizza.